Weird ATO problem

M4sonic · Apr 29, 2022

So i have a weird ATO problem i can't seem to wrap my head round.

I have a waterbox peninsula mini 25 and a D&Dcompact ato (located in the return chamber)

The past few days i thought my ato was malfunctioning since when I looked into the return chamber the water lvl was way above the sensor. So i decided to camp out by my tank to see what was going on and i noticed that the ato fills small amounts of water as it's supposed to do but the water level keeps rising for several minutes after it reaches the high fill sensor(and the ato stopped filling) .

Now i may be wrong but doesn't the water level fluctuate in the ruturn chamber only? Why would there be a delay in the rising of the water level?

blaxsun · Apr 29, 2022

The water level in the tank keeps rising, the water level in the sump keeps rising or the water level in both keeps rising after the ATO shuts off?

M4sonic · Apr 29, 2022

blaxsun said:
The water level in the tank keeps rising, the water level in the sump keeps rising or the water level in both keeps rising after the ATO shuts off?

The water level in the return chamber keeps rising for a couple minutes after the ato stops filling, I'm not sure if the level in the tank keeps rising (its only a 25gallon so not much rodi gets topped of)

blaxsun · Apr 29, 2022

M4sonic said:
The water level in the return chamber keeps rising for a couple minutes after the ato stops filling, I'm not sure if the level in the tank keeps rising (its only a 25gallon so not much rodi gets topped of)

What it sounds like is that the water from your return pump may be flowing out at a faster rate than it's returning to the AIO sump after going through your filtration.

M4sonic · Apr 29, 2022

blaxsun said:
What it sounds like is that the water from your return pump may be flowing out at a faster rate than it's returning to the AIO sump after going through your filtration.

So what could be the cause of this (or how do i solve this) cause it's really messing up my salinity.

I was under the (possibly wrong) impression that only the water level in the return chamber changes, so if i add rodi to the return chamber shouldn't that instantly change the water level in the return chamber instead of it being delayed?

M4sonic · Jun 30, 2022

Upping for visibility cause I'm still having this problem.
I've tried turning my pump down, having the ato fill the chamber before the return, and posing this problem to everyone i know (Including my lfs) and no one can figure it out.
Searching around online hasn't helped me much either.

Wasabiroot · Jun 30, 2022

Well, every compartment should change technically - the sump wouldn't work if there wasn't water flow between compartments.

It is definitely a flow thing somewhere - maybe there is some kind of siphon forming that causes an adjustment to occur in a delayed manner.
Are you able to turn your pump up?

blaxsun · Jun 30, 2022

As I alluded to above, this is most likely due to the delay between when the water starts getting added to the system, the time it takes to work its way back through the filtration and then trigger the sensor off. During this time it's probably adding more RO than it needs to. It's not overflowing though, is it?

M4sonic · Jun 30, 2022

I can turn my pump up, it's at 80% now (it's a 1200 l/h or or 320g/h) it's not overflowing but because the amount of rodi added is low i can't really tell where or when the water rises before it actually makes it to the return.

Right now i have the refill hose in the middle chamber because it seems to rise faster but it still goes way over the sensor.

Auquanut · Jun 30, 2022

I'm going to go with @blaxsun on this. When the ATO triggers, it will take just a little while for the water level to find equilibrium. The result is a water level a little bit above the sensor. Also, when your mechanical filtration (floss, socks, etc...) starts to become permeated, equilibrium is slower, resulting in a higher level. Depending on how high "way above the sensor" is, it's probably not a really big deal because the ATO won't come back on until the water level returns to normal. You shouldn't normally see a noticeable change in SG. Just a thought.

M4sonic · Jun 30, 2022

I've measured the SG difference at low and high and it's between 1.025 maybe 1.024 and 1.026 not sure how bad of a swing that is?
Cause the tank runs fine otherwise.

blaxsun · Jun 30, 2022

The salinity difference probably isn't off by that much. I typically see +/- 0.002 variance.

brmc1985 · Jun 30, 2022

M4sonic said:
So i have a weird ATO problem i can't seem to wrap my head round.

I have a waterbox peninsula mini 25 and a D&Dcompact ato (located in the return chamber)

The past few days i thought my ato was malfunctioning since when I looked into the return chamber the water lvl was way above the sensor. So i decided to camp out by my tank to see what was going on and i noticed that the ato fills small amounts of water as it's supposed to do but the water level keeps rising for several minutes after it reaches the high fill sensor(and the ato stopped filling) .

Now i may be wrong but doesn't the water level fluctuate in the ruturn chamber only? Why would there be a delay in the rising of the water level?

Can you post a picture of your setup? Make sure your ATO tube going into the tank is above the ATO container. Maybe it’s creating a syphon when it turns off.